Many commercial facilities (such as mining facilities, manufacturing facilities, chemical facilities, water treatment facilities or other facilities) use water or liquid for or as part of their process(es). Often the liquid contains various solids or particles, making it desirable or even necessary to separate out the solids from the liquid. One type of structure that is used to separate out solids from liquids is a sedimentation vessel.
Sedimentation vessels are routinely used in performing solid/liquid separation in industry. Sometimes, the names “thickener” or “clarifier” are used to generally describe sedimentation vessels. In sedimentation vessels, liquids and solids are separated from each other by gravity as described in principles explained by Stokes Law. Generally, the solids and liquids are in a slurry form and are introduced into the separation vessel via a feedwell (which is sometimes referred to as a “feed well”). However, sedimentation vessels generally suffer form a number of deficiencies. For example, in many of these vessels, the slurry is not evenly received from the feedwell into the separation vessel, thus making it inefficient to separate the solids from the liquids.
It is desirable to create a new type of feed structure (for a sedimentation vessel) that can more evenly distribute the slurry within the sedimentation vessel, thereby improving the efficiency of the separation process. Such a device is disclosed herein.
The issues associated with uneven distribution of solids into the sedimentation vessel are known and several patents have been issued addressing this problem. An example is U.S. Pat. No. 6,276,537 which uses plurality of outlet structures extending from a single chamber feedwell in an attempt to direct the slurry evenly in to the sedimentation vessel. The described embodiment of this patent is a closed bottom, except for the plurality of outlets. This structure has the potential of allowing coarse particle to settle out in the chamber. U.S. Patent Publication No. 2009/173701 also uses a single chamber system but attempts to produce an even distributed flow leaving the feedwell with a series of baffles. The described embodiment has a tapered roof that directs the feed stream from the center out to the walls were the baffles are located. In addition to employing different approaches to produce even distribution of the slurry into the sedimentation vessel, each of these single chamber patents requires combining the distribution of flow and flocculation of the feed stream in the one chamber. A dual chamber feedwell system is found in U.S. Pat. No. 7,591,946 to optimize the mixing, residence time and distribution of the solutions for flocculation and is offered as an alternative to upstream mixing tanks. The first zone receives the feed slurry, dilution water if needed and the flocculant solution stream. This first zone or chamber provides motor driven agitators to give the mixing needed to flocculate the solids. The slurry then overflows the zone into a second zone through an outlet located “centrally above the floor” of the first chamber. The location of the chamber one outlet is to provide the residence time by requiring the slurry to flow up and over the outlet. The transition between the two zones would be laminar flow to prevent breakage of the floccules produced. The slurry in the second zone flows “downward under gravity” toward a deflector cone at the bottom of this second chamber, which direct the flow evenly into the thickener.